DALLAS -- A massive spring storm plowed toward the Midwest early Wednesday after dumping more than a foot of snow on the Colorado foothills and spawning a tornado that killed nine people along the Texas-Mexico border.

Six of the victims were killed a few miles south of Eagle Pass, about 150 miles southwest of San Antonio. Four of the dead were apparently in one mobile home when the tornado hit Tuesday night, Eagle Pass Mayor Chad Foster said.

The tornado destroyed an elementary school, more than 20 nearby homes and the Eagle Pass municipal sewer treatment plant. Nobody was in the school when the tornado hit, Foster said.

"I'm out here on-site and I'm looking at what used to be an elementary school," Foster said by cell phone early Wednesday morning. "Six mobile homes are still missing."

A local hospital received 74 injured patients, including four in critical condition.

Across the border in Piedras Negras, Mexico, at least three people were killed and at least 40 were injured in the severe weather, authorities said. The storm ripped roofs from homes, toppled power poles and damaged dozens of cars and homes, said Oscar Murillo, the city's civil protection director.

In North Texas, streets flooded and roofs peeled off homes as storms began moving through Tuesday afternoon, followed by another line of severe storms about six hours later. Tornado sirens rang in several counties, and television footage showed drivers and residents being rescued from flooded cars and suburban neighborhoods.

American Airlines had about 200 flights canceled because of weather in Dallas, spokesman Billy Sanez said. The airline also diverted about 80 flights bound for Dallas-Fort Worth International Airport to other airports, including San Antonio.

In Denton County, heavy winds blew the metal roof off a restaurant and damaged several mobile homes and a commercial building under construction, said Roland Asebedo, assistant chief for Denton County's Emergency Services. No injuries were reported.

The storm system dumped heavy snow, rain and hail before roaring out of the West. Western and central Iowa received up to 3 1/2 inches of rain, and in parts of Nebraska there were reports of as much as 5 inches.

In Colorado, six buses carrying at least 60 children were stranded after being unable to travel in the storm that dropped more than a foot of snow in about two hours, said Rob Finley, assistant fire marshall for El Paso County.

Children in those buses were all accounted for late Tuesday and had been rescued and taken to shelters opened in the county, about 80 miles south of Denver.

While the sun was out in downtown Colorado Springs on Tuesday afternoon, there were whiteout conditions on the plains east of town where crews on Sno-Cats rescued dozens of motorists, said Lt. Clif Northam of the El Paso County sheriff's office.

A tornado damaged several buildings near the small town of Wild Horse about 110 miles southeast of Denver, but no injuries were reported, the Cheyenne County Sheriff's Department said.

"I was terrified," said Wild Horse resident William Skinner, 47. "It was right there, by my neighbor's, just about 200 feet away."

Evergreen, Colo., in the foothills west of Denver, reported 16 inches of snow, and other foothills towns had up to 14 inches. Some schools were closed.

"There's cars sliding off the roads everywhere," said Rick Olde, owner of Olde's Convenience Store in Evergreen. "A lot of people took their snow tires off a little early this year."

Hail the diameter of a quarter hit parts of southeastern Colorado, and authorities said some rural roads were blocked by flooding from heavy rain in northeast Colorado, northwest Kansas and southwest Nebraska.

In Nebraska, the U.S. Geological Survey reported Tuesday that most of its stream gauges along the Republic River were near or exceeded flood stage.